Provide the ability to constrain the total number of enabled devices in
the system. Once max_devs devices have been configured, subsequently
probed devices are ignored.
The max_devs parameter may be zero, in which case all CCPs are disabled.
PSPs are always enabled and active.
Disabling the CCPs also disables DMA and RNG registration.
Signed-off-by: Gary R Hook <gary.hook@xxxxxxx>
---
drivers/crypto/ccp/ccp-dev.c | 18 +++++++++++++++++-
1 file changed, 17 insertions(+), 1 deletion(-)
diff --git a/drivers/crypto/ccp/ccp-dev.c b/drivers/crypto/ccp/ccp-dev.c
index 23cef87c0950..cba96169ee36 100644
--- a/drivers/crypto/ccp/ccp-dev.c
+++ b/drivers/crypto/ccp/ccp-dev.c
@@ -2,7 +2,7 @@
/*
* AMD Cryptographic Coprocessor (CCP) driver
*
- * Copyright (C) 2013,2017 Advanced Micro Devices, Inc.
+ * Copyright (C) 2013,2019 Advanced Micro Devices, Inc.
*
* Author: Tom Lendacky <thomas.lendacky@xxxxxxx>
* Author: Gary R Hook <gary.hook@xxxxxxx>
@@ -20,6 +20,7 @@
#include <linux/delay.h>
#include <linux/hw_random.h>
#include <linux/cpu.h>
+#include <linux/atomic.h>
#ifdef CONFIG_X86
#include <asm/cpu_device_id.h>
#endif
@@ -27,11 +28,19 @@
#include "ccp-dev.h"
+#define MAX_CCPS 32
+
/* Limit CCP use to a specifed number of queues per device */
static unsigned int nqueues = 0;
module_param(nqueues, uint, 0444);
MODULE_PARM_DESC(nqueues, "Number of queues per CCP (minimum 1; default: all available)");
+/* Limit the maximum number of configured CCPs */
+static atomic_t dev_count = ATOMIC_INIT(0);
+static unsigned int max_devs = MAX_CCPS;
+module_param(max_devs, uint, 0444);
+MODULE_PARM_DESC(max_devs, "Maximum number of CCPs to enable (default: all; 0 disables all CCPs)");
+
struct ccp_tasklet_data {
struct completion completion;
struct ccp_cmd *cmd;
@@ -592,6 +601,13 @@ int ccp_dev_init(struct sp_device *sp)
struct ccp_device *ccp;
int ret;
+ /*
+ * Check how many we have so far, and stop after reaching
+ * that number
+ */
+ if (atomic_inc_return(&dev_count) > max_devs)
+ return 0; /* don't fail the load */
+
ret = -ENOMEM;
ccp = ccp_alloc_struct(sp);
if (!ccp)
